Key locks are frequently used in human passage doors for security. In these locks, rotation of a key turns a bolt works cylinder internal to the door, which in turn withdraws the door bolt against a spring bias, unlocking the door. Key locks offer the advantage of simplicity; they have only a few moving parts, and are very reliable. However, a user must have the correct key or the lock cannot be opened. If the key is lost or stolen, altering the lock to accept a different key requires that the entire lock cylinder be replaced.
Electronic door locks are also gaining in popularity. In the typical electronic door lock, the user enters a code, which generates a signal to a solenoid or other electronic means, which enables the bolt to be withdrawn. One such electronic door lock is disclosed by Gartner, U.S. Pat. No. 4,899,562. Electronic locks are also easy to use, and only require the user or remember the combination to gain entry. The combination can easily be shared, and can also be easily changed, increasing the convenience of the lock.
Accordingly, it would be most advantageous if the benefits of both key locks and electronic locks could be utilized in a single lock, wherein a door could be unlocked with either method. Further, it would be beneficial if an existing key lock could be simply retro-fitted with additional components to add the electronic lock, so that both locks use the same door bolt. It is anticipated that both business and home users of door locks would prefer the simplicity of a key lock with the convenience of an electronic lock.